Field of the Invention
The present invention relates to a multi-source radiation generator applicable to, for example, non-destructive X-ray radiography in the field of medical and industrial equipment, and relates also to a radiographic imaging system using the multi-source radiation generator.
Description of the Related Art
Recently, in medical inspections, such as mammography, tomosynthesis imaging is performed as a technique to obtain information in a depth direction of a sample. In tomosynthesis imaging, the sample is irradiated with radiation from a radiation generator which moves over a limited arc and emits the radiation at plural angles, and the sample is imaged by obtaining plural images. The obtained plural images are reconstructed using specific algorithms to form a tomographic image.
More specifically, in conventional tomosynthesis imaging, typically, radiographic imaging is performed by applying radiation to the sample while a radiation tube is moved in a predetermined angle range (±7.5° to ±25°) with respect to the sample. However, there have been the following problems: an artifact may be produced in an image because the radiation tube is moved at the time of radiographic imaging of the sample; and prolonged radiographing time is required because a mechanical movement takes time. Further, there has been a possibility that a subject feels fear at the movement of the radiation tube.
U.S. Pat. No. 8,094,773 discloses a technique to obtain a three-dimensional X-ray radiographic image by performing tomosynthesis imaging using plural X-ray sources that are arranged in series.
A multi-source radiation tube in which plural radiation sources are arranged in series is advantageous in that the size of the entire apparatus may be reduced and that the multi-source radiation tube may be manufactured in a simplified and affordable manner. An integrally formed radiation tube is especially advantageous in manufacture.
However, since a distance between the radiation source and the subject varies depending on the position of the radiation source, there is variation in an exposure dose. For this reason, there has been a problem that, there is variation in the exposure dose in the obtained plural images and, therefore, a tomographic image obtained by reconstructing these images is not necessarily favorable.